May 11, 2018

A Wildfire Likely Spawned a Severe Thunderstorm in Texas

The ground can influence the weather in ways we don't always realize are happening. Cities warm up the atmosphere around them. Air lifting over the sides of mountains can create rain and snow. Wildfires can cause billowing cumulonimbus clouds. And some of those fires can even trigger thunderstorms like the supercell that popped up over the Texas Panhandle on Friday afternoon.

Satellite and radar imagery showed smoke rising from a large wildfire southeast of Amarillo, Texas, on Friday afternoon. The fire grew in size through the afternoon and the heat generated by the fire spawned a rather hefty pyrocumulonimbus cloud.

There was enough instability over Texas and Oklahoma on Friday to support the development of thunderstorms, but only if the cap broke. A "cap" is a nickname for an inversion layer, or a layer of warmer air sitting atop a layer of colder air. An inversion layer can prevent air from freely rising through the atmosphere, stifling the development of showers and thunderstorms. Stronger caps are harder to erode.

Something needs to break the cap in order for a storm to form. Strong surface heating during the day can raise low-level temperatures enough that rising air can reach a speed at which it breaks through the cap like cheap aluminum foil. Sometimes it takes forcing from a feature like a cold front or a sea breeze to give rising air the extra oomph it needs to break through the inversion.

Today, the force that helped break the cap was the heat from the fire.

You can follow the progress of the wildfire using GOES-East's shortwave infrared product. The heat generated by the fire makes the affected area southeast of Amarillo show up as a black splotch on satellite imagery. Smoke billowing northeast of the fire starts off a darker shade of gray at first, but the smoke eventually becomes obscured by the pyrocumulonimbus clouds as the afternoon wears on.

The thunderstorm developed in the late afternoon. The storm was able to tap into the instability already present and organize into a supercell, complete with at least one report of quarter-size hail and a beautiful overshooting top and expansive anvil that shows up well on visible satellite imagery.

You can even track the smoke and thunderstorm on radar imagery out of Amarillo. The smoke appears on radar as the steady stream of returns flowing northeast on the eastern side of the radar. The thunderstorm develops around 5:00 PM CDT and continues to grow as it approaches the Oklahoma border as it feeds off of instability in the atmosphere.

While fire-induced thunderstorms are rare, it's not out of the question when there's a large fire in the right environment. The devastating fires in and around Fort McMurray, Alberta, back in May 2016 were strong enough to spawn pyrocumulonimbus clouds that caused lightning, which, in turn, started even more fires.

[Vis/IR Combo: Dennis Mersereau (data via AllisonHouse) | Radar/Sat.: College of DuPage | Model Image: PivotalWeather]

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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I contribute to The Weather Network as a digital writer, and I've written for Forbes, the Washington Post's Capital Weather Gang, Popular Science, Mental Floss, and Gawker's The Vane. My latest book, The Skies Above, is now available. My first book, The Extreme Weather Survival Manual, arrived in October 2015.